1. Field of the Invention
The present invention relates to a process for sterilizing a filtration device, and more particularly to a process for the steam sterilization of a filtration device having a hollow fiber type module.
2. Description of the Prior Art
As methods for sterilizing a semipermeable membrane filtration device, the method of using chemicals such as sodium hypochlorite or a heating sterilization method utilizing hot water at a temperature of about 90.degree. C. have been employed.
In the method where chemicals are used, there has been employed the sterilization method in which a sterilizer such as sodium hypochlorite, hydrogen peroxide and formalin etc. is filtered through a semipermeable membrane disposed in a semipermeable membrane filtration device from the raw water side of the device. However, according to this method, if air remains within the pipelines due to the structure of the pipelines or instruments, some portions thereof are not filled with the sterilizer and thus are insufficiently sterilized.
On the other hand, according to the hot water sterilization method, even when sterilization is effected with hot water at a temperature of about 90.degree. C., heat resistant spores which cannot be killed at about 90.degree. C. may sometimes exist, or there may be air or dead space remaining in the filtrate pipelines, whereby such portions cannot be effectively replaced with hot water thereby producing an insufficient sterilzing effect.
Further, after sterilization is performed with a sterilizer as described above, it is necessary to wash out the sterilizer. For this purpose a thorough rinsing with water is required to be performed, whereby not only a long time is required, but also the waste water must be disposed of.
In the prior art, no filtration device is known which uses a hollow fiber type membrane module which can with stand steam sterilization. This is because the hollow fiber type module generally employs hollow fiber membranes fixed at both ends onto a module case with a sealing material, whereby the membrane properties are lowered under the high temperature and high pressure conditions of steam sterilization or leaks may occur at the sealed portions.